Many compounds have been proposed, in the prior art, as additives for improving the behavior at temperatures and more particularly the properties of cold filterability of oil middle distillates.
They may consist of mere polymers such as, for example, ethylene homopolymers. Some of them are mentioned, by way of example, in the West-German Patent DE No. 856,682 and the U.S. Pat. No. 3,640,824, both describing the use of branched polyethylenes of high number molecular weight, whereas the british patent GB No. 847,777 and the U.S. Pat. No. 3,454,379 recommended, on the contrary, the use of branched polyethylenes of low number molecular weight (lower than 5,000).
However, the use of only branched polyethylene is not sufficient to obtain satisfactory properties of cold filterability; this is also true for the use of various copolymers of ethylene with another co-monomer such, for example, as vinyl acetate, .alpha.-olefins, esters or diesters having an olefinic double bond.
Much better results concerning the improvement of cold filterability of oil middle distillates have been obtained by using mixtures of additives.
Among the numerous disclosed compositions, those which do not comprise polyethylene as homopolymer or as a co-polymer may be first mentioned. Thus the French patent FR No. 2,347,435 discloses the synergic action of an alkyl-aromatic derivative associated either to a hydrogenated 1,4-polybutadiene or to a hydrogenated copolymer of 1,4 polybutadiene with a second dialkene compound. U.S. Pat. No. 2,917,375 indicates the synergic properties of micro-crystalline paraffin waxes admixed with acrylic and/or methacrylic polymers. U.S. Pat. No. 4,140,492 mentions the synergic action of two compounds: the first one results from the action of boron compounds on Mannich bases of phenol compounds, while the second may be an amorphous hydrocarbon or a hydrogenated polybutadiene.
Compositions wherein one of the constituents is an ethylene copolymer may also be mentioned. By way of example, U.S. Pat. No. 3,660,057 discloses the association of hydrocarbon fractions free of n-paraffins which copolymers of ethylene and .alpha.-olefins of 3 to 16 carbon atoms, or with copolymers of ethylene and acids, anhydrides or esters having an olefinic double bound. The U.S. Pat. No. 3,640,691 discloses the association of a minor paraffinic fraction, containing n-paraffins of 24-40 carbon atoms with ethylene/vinyl acetate copolymers. French Pat. No. 2,061,457 associates two copolymers of ethylene and vinyl acetate of different molecular weights. Japanese patent JP No. 57,209,995 discloses a synergic action between a residual heavy oil and a copolymer of ethylene with an ester of a carboxylic acid having ethylenic bonds. The European patent EP No. 0,074,208 discloses a synergic action on the filterability limit temperature of fuel oils between, on the one hand, a copolymer of ethylene and alkoxyalkyl(meth)acrylate and, on the other hand, a copolymer of ethylene associated either with a vinyl ether or with an alkyl ether of unsaturated acid.
U.S. Pat. No. 3,961,916 teaches the synergism between two copolymers both composed of ethylene, copolymerized either with vinyl esters or with alkyl(meth)acrylates. U.S. Pat. No. 4,153,424 discloses the synergic effect of a copolymer of ethylene and alkyl acrylates associated with a homo- or copolymer of alkyl acrylate and/or methacrylate. Among these types of compositions having a synergic action, were also described compositions comprising three different compounds. Thus, the Japanese patent JP No. 56,043,391 discloses the synergic action of a chlorinated polyethylene, a branched polyethylene, an alkenyl-succinamide. U.S. Pat. No. 3,892,909 teaches a synergic effect of three compounds:
(A) A mono-amide or mono-esterified derivative of an unsaturated dicarboxylic acid; PA0 (B) A copolymer of ethylene with an ester of an unsaturated mono- or di-carboxylic acid, a C.sub.3 -C.sub.16 .alpha.-olefin or vinyl chloride; and, PA0 (C) A micro-crystalline wax free of n-paraffins, or an alkyl aromatic compound. PA0 Finally, compositions wherein one of the constituents is polyethylene can be mentioned. PA0 (A) polyethylene or a copolymer of ethylene with a 3-18 carbon atoms .alpha.-olefin, and PA0 (B) a copolymer of ethylene with an unsaturated carboxylic monoester. PA0 (A) being either polyethylene or a copolymer of ethylene with esters having ethylenic unsaturations, and PA0 (B) being an alkyl poly(meth)acrylate. PA0 (A) polyethylene or chlorinated polyethylene or a copolymer of ethylene with an .alpha.-olefin or vinyl or (meth)acrylic ester, and PA0 (B) sulfonated copolymers obtained by reacting sulfurous anhydride with .alpha.-olefins mixtures. PA0 (A) polyethylene or a copolymer of ethylene with either a vinyl ether, or an alkyl(meth)acrylate, or an .alpha.-olefin, and PA0 (B) alkyl poly(meth)acrylates. PA0 (A) polyethylene or chlorinated polyethylene or a copolymer formed from ethylene and alkyl acrylate or vinyl acetate or still a hydrogenated copolymer of butadiene and isoprene, and PA0 (B) the reaction product of linear N-alkyl polyamines with saturated or unsaturated cyclic anhydrides, optionally substituted with a hydrocarbon group comprising 1 to 6 carbon atoms. PA0 (A) polyethylene or chlorinated polyethylene or a copolymer of ethylene with either an .alpha.-olefin or an unsaturated monoester, or an unsaturated diester, PA0 (B) bees-wax or ozokerite or a mixture of .alpha.-olefins havins 24 to 50 carbon atoms. PA0 (A) polyethylene or a copolymer of ethylene with unsaturated mono or diester, and PA0 (B) either polymerized .alpha.-olefins, or a copolymer of dialkyl fumarate with either vinyl acetate or alkyl methacrylate. PA0 (A) a polyethylene or chlorinated polyethylene or copolymer of ethylene with an unsaturated mono or diester, an .alpha.-olefin or vinyl chloride, PA0 (B) a polymer or copolymer derivating from at least one of the alkyl diesters of unsaturated carboxylic diacids and .alpha.-olefins. PA0 (A) a polyethylene, a chlorinated polyethylene, a copolymer of ethylene/vinyl acetate or a compound of alkyl aromatic type; and PA0 (B) a copolymer obtained from a N,N'-dialkyl maleamide derivative and an .alpha.-olefin of 8-30 carbon atoms. PA0 (a) at least one linear .alpha.-olefin PA0 (b) at least one unsaturated .alpha.,.beta.-dicarboxylic compound, such as diacid, light alkyl diester or anhydride, and PA0 (c) at least one alkyl ester of an unsaturated monocarboxylic acid; PA0 a constituent (A) which is at least one ethylene polymer, and PA0 a constituent (B) which is at least one polymeric compound which may be defined as resulting from the condensation of at least one compound with a primary amine group such as hereinafter defined, with a copolymer comprising: PA0 (a) recurrent units from at least one linear .alpha.-olefin, PA0 (b) recurrent units derived from at least one unsaturated .alpha.,.beta.-dicarboxylic compound, such as a diacid, light alkyl diester or anhydride; and PA0 (c) recurrent unit from at least one alkyl ester of an unsaturated aliphatic monocarboxylic acid or from at least one vinyl ester of a saturated aliphatic monocarboxylic acid. PA0 R is a saturated aliphatic monovalent radical containing 1 to 30 carbon atoms; PA0 Z may be either an oxygen atom or a divalent --NH-- or --NR'-- group, R' being a monovalent aliphatic radical, preferably linear, comprising 1 to 30 carbon atoms and preferentially 12 to 24 carbon atoms, n is an integer from 2 to 4, and m is an integer from 1 to 4, or may also be zero, when Z is NH.
Thus, U.S. Pat. No. 3,640,824 discloses the association of a highly branched polyethylene of number molecular weight higher than 6,000 with a micro-crystalline wax and/or with naphthalene and/or asphaltenes.
U.S. Pat. No. 3,661,541 mentions the synergism betweeen:
French patent FR No. 2,305,493 teaches the synergism between two compounds (A) and (B):
French patent FR No. 2,324,711 indicates the syngergism between:
French patent FR No. 2,305,492 discloses the synergism between:
U.S. Pat. No. 3,166,387 discloses the synergic action of polyethylene of low molecular weight associated with a secondary or tertiary amine salt of carboxylic acid.
French patent FR No. 2,490,669 discloses a synergic composition formed from:
U.S. Pat. No. 4,019,878 discloses a composition having a synergic effect, formed by:
U.S. Pat. No. 4,175,926 indicates a composition having a synergic effect, obtained from:
British patent BG No. 1,469,016 mentions a synergic mixture consisting of:
Japanese patent JP No. 54,086,505 teaches a composition having a synergic effect, prepared from:
However, none of these compositions is able to confer to the oil middle distillates, and particularly to gas-oils and fuel-oils, satisfactory properties at cold temperatures, as a whole.
On the other hand, the applicants have previously described certain additives which, by a mechanism not yet clear, may reduce the temperature of formation of the first paraffin crystals (particularly in the French patent application FR No. 2,528,066, filed on June 4, 1982). Briefly stated, this additive may be described as the product obtained by reaction, of a terpolymer comprising:
with at least one compound with a primary amine group complying with one of the general formulas: EQU R--Z[(CH.sub.2).sub.n NH].sub.m H (I)
and EQU HO--CH.sub.2 --R"--NH.sub.2 (II)
wherein R is a saturated aliphatic monovalent radical of 1-30 carbon atoms, Z is selected from --NH--, or --NR'-- groups, wherein R' is a saturated aliphatic monovalent radical of 1-30 carbon atoms, and the oxygen atom --O--, n is an integer from 2 to 4, m is zero or an integer from 1 to 4; and R" is a saturated aliphatic divalent radical of 1-18 carbon atoms.
These additives, when added to gas-oil cuts, for example at concentrations of about 0.1% by weight, have shown a favorable action, mainly on the cloud point thereof, but also on their filterability limit temperature as well as on their pour point temperature.